Actually, Wikipedia works pretty well on a smart phone. It's some form of responsive or adaptive technology, but I've found it useful. Can't speak to the others.
Today I did a few searches for my sites from my iPhone; hadn't done that for a while. WAY impressed with the way the sitelinks look and work now; great sitelinks with arrows on each one to drill down. That may only exist for the top position though (I was only searching on obvious keyword strings) I dunno how long they've looked like this, it's the first time I noticed it. But it looked to me like a pretty good user experience getting the smartphone user right to the correct set of pages.